I've tried to do some thinking about the rather difficult and controversial topic of the Mosiac Law, and have so far arrived at the following:
1. The Mosaic Law was never intended as a means of salvation and is not thought of in those terms.
2. However, the law does require a certain 'doing' in order to receive blessings i.e. blessings and curses of Deuteronomy.
3. The demand of the law is very strong ("be holy as I am holy", "Love the LORD", "love your neighbour"). To break any of the law is to break the whole law.
4. This Law could not be kept, not because there's something wrong with it, but because we are born in sin and cannot keep it, and the Mosaic administration did not bring the Spirit.
5. The fact that it cannot be kept is shown by three things in the Old Testament:
a. the story of Israel's continual sin and punishment (in the histories and prophets)
b. God's faithfulness to the covenant in spite of them breaking it,
c. and the promise of a new covenant and law to be written on the heart (which
implies the insufficiency of the first Law).
From the NT perspective, the people lacked the power of resurrection life and the Spirit.
6. The OT believer was therefore imprisoned by the contrast between the law's demands and his ability to keep it. The law essentially reveals the reality of sin and a need for a changed heart.
7. The disobedience of Israel to the Law, and subsequent judgment, contrasts with the grace of the promise shown throughout the OT. The grace of the Abrahamic promise is the source of Israel's salvation and blessing. The curses of the Mosaic covenant are not absolute as the LORD acts according to the grace in the promise (seen, for example, in the restoration of the people to the land).
8. There is, therefore, a tension (though not an old-fashioned law-gospel tension) in the OT between law and promise which is not resolved until the coming of Jesus. How can Israel be righteous inheritors of the promise? How can the demand of the law and the promise of blessing be reconciled?
9. The OT believer is saved by his dependence upon the promises given to Abraham, and the hope of the Messiah who will fulfil the law and bring righteousness.
10. Christ is the end/fulfilment of the law - He is the true Law and the inheritor of the promise and so the tension between demand and promise is resolved in Him and the gift of the Spirit.
More thoughts soon on the Law and the NT believer.